Dual-Frequency Radar Transmission for High-Accuracy Doppler Estimation
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Solution Overview
Problem
Existing radar apparatuses, particularly MIMO radars, face challenges in accurately detecting target objects due to ambiguity in Doppler frequency estimation, especially when using time-division multiplex transmission, which limits the detectable Doppler frequency range and introduces ambiguity, and Doppler multiplex transmission with unequal intervals faces issues with demultiplexing errors and angle measurement inaccuracies.
Innovation Solution
A radar apparatus that transmits signals with different central frequencies from multiple antennas, employing Doppler multiplex transmission with unequal intervals to extend the detectable Doppler frequency range and improve demultiplexing accuracy by utilizing reception power level differences to estimate Doppler frequencies accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-division multiplex transmission is used to transmit signals from multiple antennas, then the detectable Doppler frequency range is limited, but the system complexity is reduced
Solution Approach 1:
The transmission signals from multiple antennas are segmented in time, with each antenna transmitting at different time intervals. This time-division multiplexing approach allows the radar system to process signals from multiple antennas sequentially rather than simultaneously, reducing the complexity of signal processing while maintaining the ability to estimate Doppler frequencies accurately within the constrained time window
Solution Approach 2:
The radar system employs periodic transmission of signals from different antennas in a cyclic manner. Each antenna transmits signals at regular time intervals, creating a periodic pattern that enables the receiver to distinguish between signals from different antennas through timing information, thereby managing system complexity while preserving measurement capability
2Measurement precision
If Doppler multiplex transmission with unequal intervals is used to extend detectable Doppler frequency range, then the detectable Doppler frequency range is extended, but demultiplexing errors and angle measurement inaccuracies occur
Solution Approach 1:
The patent employs asymmetric time intervals between transmissions from different antennas, where the time intervals are deliberately made unequal to create distinct temporal signatures for each antenna's signal. This asymmetry allows the receiver to differentiate between signals from different antennas even when they overlap in frequency, extending the detectable Doppler frequency range while maintaining demultiplexing accuracy through the unique timing patterns
Solution Approach 2:
The system incorporates feedback mechanisms where the receiver measures the actual time intervals and signal characteristics, then uses this information to adjust and refine the demultiplexing process. This feedback loop compensates for timing variations and maintains angle measurement accuracy despite the use of unequal transmission intervals, ensuring reliable signal separation across the extended frequency range
3Measurement precision
If multiple transmission signals with different central frequencies are transmitted simultaneously, then the detectable Doppler frequency range is extended, but signal interference and processing complexity increase
Solution Approach 1:
The patent extends the detection capability by adding a frequency dimension to the time-division multiplexing scheme. Multiple transmission signals with different central frequencies are transmitted at different time intervals, creating a two-dimensional signal space (time-frequency) that allows the receiver to distinguish between signals from different antennas and different Doppler frequencies, thereby extending the detectable range while managing processing complexity through structured signal design
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high-accuracy detection of target objects over a wider Doppler frequency range, reducing ambiguity and improving demultiplexing performance, thereby enhancing the radar's ability to distinguish between multiple reflected waves from objects at similar distances.
Implementation Method 1
a radar apparatus capable of detecting a target object with high accuracy... Doppler frequency estimation... extend the detectable Doppler frequency range... estimate Doppler frequencies accurately
Data Source
AI summary
Provided is a radar apparatus that detects a target object with high accuracy. The radar apparatus includes: transmission circuitry, which, in operation, alternately outputs a first transmission signal with a first central frequency and a second transmission signal with a second central frequency higher than the first central frequency for each transmission period; and one or a plurality of transmission antennas, which, in operation, transmit the first transmission signal and the second transmission signal. The second central frequency is higher than a frequency (1+1/Nc) times the first central frequency, where Nc is an integer indicating a number of times of transmission of each of the first transmission signal and the second transmission signal for the each transmission period within a predetermined duration.